Airway device

ABSTRACT

An airway device for human or animal use comprising an airway tube having a distal end and a proximal end, the distal end of which is surrounded by a laryngeal cuff, wherein the cuff is non-inflatable and is pre-formed in a shape such that a face region of the cuff is adapted to fit snugly over the laryngeal inlet of a patient, and wherein the external profile of the tube is substantially uniform between the distal end of the tube where it starts to meet the cuff and the proximal end of the tube, and wherein the face region of the cuff is formed from a material with a Shore hardness on the A scale of between 0 to 30.

FIELD OF THE INVENTION

The present invention relates to medical devices and is particularlyapplicable, but in no way limited, to laryngeal airway devices and totheir methods of manufacture.

BACKGROUND TO THE INVENTION

A wide variety of devices are known and are currently used inspontaneously breathing anaesthetized patients, during recovering afteranaesthetics, in weaning of a certain group of patients in intensivecare, or during resuscitation to provide a clear and hands-free airway.A number of these devices are listed in the applicant's co-pendingearlier application GB2,393,399A (Nasir), the text of which is herebyimported by reference and which is intended to form an integral part ofthis disclosure. GB2,393,399A describes a new type of airway devicewhich has a soft laryngeal cuff adapted to fit anatomically over andform a seal with the laryngeal structure of a patient. An essentialfeature of certain embodiments of this device is a so-called buccalcavity stabiliser, located around the airway tube, and which is designedto nest with the anterior aspect of the patient's tongue.

The laryngeal cuffs on these devices are generally non-inflatable, butrather are formed from a soft, deformable material that can adapt to theindividual detail of the patient's laryngeal inlet to form asatisfactory seal. It was precisely because of the very soft, deformablenature of these cuffs that it was considered necessary to incorporatesome form of stabiliser to locate the cuff during insertion and tomaintain a good gas-tight contact with the laryngeal inlet at all timesduring use. It should be borne in mind that “use” can involve thepatient in many hours on the operating table under anaesthesia and canalso involve use in accident and emergency situations involving hostileconditions that are non-ideal for such treatments.

It has now unexpectedly been discovered that a stabiliser, whilst stilldesirable, is not essential to achieve a good gas-tight seal between thecuff and the laryngeal inlet of the patient. Since a buccal cavitystabiliser adds both weight and cost there are positive advantages ineliminating this feature from the design. Weight and cost are bothimportant features, particularly where the item is intended as a singleuse or disposable item.

It has also been deemed possible to reduce the material in the laryngealcuff by manufacturing as a preformed/prefilled anatomical cuff, and bypotentially removing the gastric channel.

It is an object of the present invention to provide an airway devicethat is both simple and effective to use and cost-effective tomanufacture.

Where a single use item is concerned, cost of manufacture, andminimising this cost, is important. A further objective of the presentinvention is to provide cost-effective methods for manufacturing airwaydevices that enable the unit cost per item to be minimised.

It is also an object of this invention to satisfy the requirements ofclinical situations where a buccal cavity stabiliser would not enhance,but impede the operation. For example in many opthamalogical, andmaxillofacial or dental surgery the use of a reinforced tube arepreferable, as the tube can flexibly moved to one side to continue toprovide an airway for the patient, whilst not interfering with theoperation. In summary, where it might be advantageous to have an airwaydevice with a buccal cavity stabiliser in some applications, we havediscovered that there are several applications where this isdisadvantageous. In fact there are several applications where it is justnot practical to have a buccal cavity stabiliser.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides an airway device asdescribed in the accompanying claims.

Accordingly, according to a first embodiment there is provided an airwaydevice for human or animal use comprising an airway tube having a distalend and a proximal end, the distal end of which is surrounded by alaryngeal cuff, wherein the cuff is non-inflatable and is pre-formed ina shape such that a face region of the cuff is adapted to fit snuglyover the laryngeal inlet of a patient, and wherein the external profileof the tube is substantially uniform between the distal end of the tubewhere it starts to meet the cuff and the proximal end of the tube, andwherein the face region of the cuff is formed from a material with aShore hardness on the A scale of between 0 to 30.

Such an airway device is both efficient in operation and cost-effectiveto manufacture.

Preferably the face region of the cuff is formed from a material ofShore hardness on the A scale of between 0 and 20 and more prefereably 0to 5.

Preferably the profile of the airway tube is substantially circular.

In an alternative embodiment the profile of the airway tube issubstantially elliptical.

Preferably the device further comprises a gastric tube passagewayextending from the distal end of the airway tube to the proximal end ofthe cuff.

Preferably the gastric tube passageway is housed substantially withinthe body of the device.

Preferably the distal end exit of the gastric tube passageway exits thecuff centrally, that is along the line of the central longitudinal axisof the device.

Alternatively the distal end exit of the gastric tube passageway may bedisplaced to one side of the central longitudinal axis of the device

If the end exit of the gastric tube passageway is displaced it ispreferred that the distal end exit of the device is displaced to theright of the central longitudinal axis of the cuff, as viewed from theopen face of the cuff, in other words to the right-hand side of thepatient when the device is in use. This is for ease of manufacture.

In a particularly preferred embodiment the device further comprises oneor more flexible flanges extending around the opening in the face regionof the cuff.

Preferably the flexible flanges extend substantially around the entirecircumference of the opening in the cuff.

Preferably a plurality of flanges are provided said flanges being spacedapart radially around the opening one from another such that the flangesare substantially concentric.

Advantageously said device further comprises a connector adapted toconnect the proximal end of the airway tube to a gas supply.

Preferably said connector extends into said airway tube and at leastpart way along the length of said airway tube to act as a bite protectorto prevent a patient from constricting the airway tube by biting on it.

Preferably said connector fits into an internal annular recess at theproximal end of the airway tube such that the diameter, or internalcross-section of the airway tube where the tube is non-circularinternally, remains substantially constant along the length of the tubewhen the connector is in place.

Preferably the distal end of the connector abuts in use a shoulder inthe airway tube to prevent the connector from passing into the airwaytube beyond a certain point. This provides a positive fit for theconnector which seats on a shoulder or recess within the tube, andresults in lower resistance to airflow through the device.

Preferably the face of the laryngeal cuff is adapted to form ananatomical fit over the laryngeal inlet of a patient incorporatesprotuberances designed to form a good seal with the pyriform fossae andaryepiglottic folds of the laryngeal inlet of the patient.

Preferably the face of the laryngeal cuff adapted to form an anatomicalfit over the laryngeal inlet of a patient incorporates protuberancesdesigned to form a good seal with the valleculae, epiglottis,aryepiglottic folds, pyriform fossae and around the anterior aspect ofthyroid & cricoid cartilages. The distal tip of the device positionsitself into the recess created by the posterior aspect of the lowerlarynx below the posterior cartilages, above the opening of theoesophagus, not only to help create an airway seal but also to act as aphysical wedge to prevent the possibility of regurgitation.

Preferably the face of the laryngeal cuff adapted to fit anatomicallyover the laryngeal framework of a patient incorporates grooves designedto allow passage of vital arteries, veins and nerves supplying thelaryngeal framework.

Preferably the distal tip of the laryngeal cup is so sized and shaped asto remain above the upper oesophageal sphincter in use.

Preferably the distal tip of the laryngeal cup is substantially concavein shape.

Preferably the face of the laryngeal cuff and the airway tube are formedfrom materials of different Shore hardness.

In an alternative embodiment the face of the laryngeal cuff and theairway tube are formed from material of substantially the same Shorehardness.

Preferably the airway tube together with the back or dorsal part of thecuff are made from material of one Shore hardness and the face of thecuff is made from a material of a different Shore hardness, such thatthe face of the cuff is made of a softer material than the airway tubeand the back or dorsal part of the cuff.

According to a further aspect of the invention there is provided amethod of manufacturing an airway device suitable for human or animaluse, said airway device comprising an airway tube having a distal endand a proximal end, the distal end of which is surrounded by anon-inflatable laryngeal cuff, said method comprising the steps of:

-   (i) providing a mould, the mould Including interior walls defining    an interior volume which defines the shape of the airway device;-   (ii) introducing a liquid plastics material into the hollow interior    volume of the mould;-   (iii) optionally introducing a second liquid plastics material into    said mould where it is required that the airway device is made from    materials of different Shore hardness;-   (iv) allowing the plastics material to solidify;-   (v) removing the airway device from the mould.

Preferably said method also comprises the step of inserting into saidmould a connector suitable for connecting to an anaesthetic gas supply,such that, after the moulding process is complete, the connector becomesattached to the airway device.

According to a further aspect of the invention there is provided amethod of manufacturing an airway device suitable for human or animaluse, said airway device comprising an airway tube having a distal endand a proximal end, the distal end of which is surrounded by anon-inflatable laryngeal cuff, said method comprising the steps of:—

-   (i) providing an airway tube;-   (ii) providing a mould, said mould including interior walls defining    an interior volume which defines the shape of a laryngeal cuff;-   (iii) inserting said airway tube into said mould;-   (iv) introducing a liquid plastics material into the hollow interior    volume of the mould;-   (v) optionally introducing a second liquid plastics material into    said mould where it is required that the cuff of the airway device    is made from materials of different Shore hardness;-   (vi) allowing the plastics material to solidify;-   (vii) removing the airway device from the mould.

Preferably said airway tube is formed by an extrusion process.

In a still further aspect of the present invention there is providedmethod of manufacturing an airway device suitable for human or animaluse, said airway device comprising an airway tube having a distal endand a proximal end, the distal end of which is surrounded by anon-inflatable laryngeal cuff, said method comprising the steps of:—

-   (i) providing a mould, the mould including interior walls defining    an interior volume which defines the shape of a laryngeal cuff;-   (ii) introducing a liquid plastics material into the hollow interior    volume of the mould;-   (iii) optionally introducing a second liquid plastics material where    it is required that the airway device is made from materials of    different Shore hardness;-   (iv) allowing the plastics material to solidify;-   (v) removing the airway device from the mould;-   (vi) providing an airway tube;-   (vii) bonded said airway tube to said laryngeal cuff.

In a still further aspect of the invention there is provided a method ofmanufacturing an airway device suitable for human or animal use, saidairway device comprising an airway tube having a distal end and aproximal end, the distal end of which is surrounded by a non-inflatablelaryngeal cuff, said method comprising the steps of:—

-   (i) providing an airway tube;-   (ii) providing a mould, said mould including interior walls defining    an interior volume which defines the shape of a laryngeal cuff and    which substantially encapsulates the airway tube;-   (iii) inserting said airway tube into said mould;-   (iv) introducing a liquid plastics material into the hollow interior    volume of the mould, to form the back of the cuff and substantially    cover the rigid airway tube-   (v) optionally introducing a second liquid plastics material into    said mould where it is required that the cuff of the airway device    is made from materials of different Shore hardness;-   (vi) allowing the plastics material to solidify;-   (vii) removing the airway device from the mould.

Preferably said airway tube is formed by an extrusion process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the accompanying drawings in which:—

FIG. 1 illustrates front, side and rear elevational views of an airwaydevice according to a first embodiment of the present invention having asubstantially circular profile airway tube;

FIG. 2 illustrates various perspective views of the embodiment shown inFIG. 1;

FIG. 3 shows front, side and rear elevational views of an airway deviceaccording to a second embodiment of the present invention having asubstantially elliptical profile airway tube;

FIG. 4 illustrates various perspective views of the embodiment shown inFIG. 3;

FIG. 5 illustrates various perspective views of an embodiment without agastric tube passageway;

FIG. 6 illustrates front, side and rear elevational views of an airwaydevice according to a further embodiment of the present invention;

FIG. 7 illustrates various perspective views of the embodiment shown inFIG. 6;

FIG. 8 shows enlarged rear, side and front elevational views of alaryngeal cuff; and

FIG. 9 shows an enlargement of a cuff, detailing the split line betweendifferent plastics which would be present if the cuff is to be formed bymaterials of two different shore hardnessess;

FIG. 10 illustrates a connector which can also act as a bite protector;

FIG. 11 illustrates a front elevational view of a laryngeal cuff inwhich the gastric tube passageway exits on the mid-line or centrallyfrom the tip of the cuff.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described below by way ofexample only. These examples represent the best ways of putting theinvention into practice that are currently known to the applicantalthough they are not the only ways in which this could be achieved.

As used herein, the anatomical terms “anterior” and “posterior,” withrespect to the human body, refer to locations nearer to the front of andto the back of the body, respectively, relative to other locations. Inthe context of this description, the term “proximal” means the end ofthe device, or portion thereof, closest to the connection to theanaesthetic breathing system. The term “distal” means the end of thedevice, or portion thereof, furthest from the anaesthetic breathingsystem or alternatively, the cuff end of the device. The term “lateral”refers to a location to the right or left sides of the body, relative toother locations. “Bilateral” refers to locations both to the left andright of the body, relative to other locations. The anatomical term“medial” or “medially” refers to a location toward the centre or midlineof the body, relative to locations both to the left and right of thebody.

Referring to FIG. 1, this illustrates front, side and rear elevations ofan airway device according to a first embodiment of the presentinvention, generally shown as 10. This comprises an airway tube 11,which at its proximal end 12 terminates in a 15 mm or other connector 18suitable for connection to an anaesthetic breathing system ofconventional type. Formed around the distal end 13 of the airway tube isa laryngeal cuff or cup 14 adapted in its shape and contours tocorrespond with the laryngeal inlet region of a patient. In this contextthe terms cuff and cup have an equivalent meaning. They refer to theelement of the device at the distal end of the airway tube that isadapted to cover and form a seal with the laryngeal inlet of the patientin use. The anatomy of the laryngeal inlet region of a human is wellknown to the expert. It is illustrated in some detail in FIG. 1 ofGB2,393,399 and the key thereto, both of which are imported herein byreference.

The cuff 14 has an opening 17 in a face or front region of the cuff andthe back or dorsal part of the cuff is closed. The opening 17 in theface of the cuff connects directly to the airway tube 11 such that gasis free to flow from the connector 18 through the airway tube and out ofthe open face of the cuff.

The particular cuff shown in FIG. 1 incorporates in the cuff facepronounced and discernable bulges or protuberances 15, 16 designed toform a good seal with the piriform fossae and aryepiglottic folds. Itwill be appreciated that the outbulgings in the cuff at 15 and 16 arepositioned antero-laterally to the laryngeal framework and give ananatomical seal by fitting into the piriform fossae and aryepiglotticfolds and space postero-inferior to the thyroid and cricoid cartilages,and the posterior cartilages (corniculate and cuneiform). Thus, in sideelevation, the face of the cuff is not a flat planar surface butincludes regions that protrude above the general plane of the cuff face.Additionally, there may optionally be regions which lie below thegeneral plane of the cuff face. These shapings and the general size,shape and configuration of the surface of the cuff face around opening17 are an important feature of the invention.

Thin, flexible, featherlike flanges 20 and 21 extend substantiallyaround the circumference of the opening 17 in the face region of thecuff. These flanges are preferably formed as an integral part of themoulding of the cuff and, because of the very soft nature of thematerial used to form the cuff, these flanges are particularly soft andpliable. Their purpose is to make allowance for any individual patientvariation in the laryngeal inlet shape and to contribute to forming anefficient and effective seal between the cuff and the laryngealstructures. By this design, and by designing the cuff to be a closeanatomical fit, the obtainable seal pressure from experimental trials iswell within the range of 12-40 cm H₂O, which is sufficient forventilation.

These flanges need not completely encircle the opening 17 as shown inFIG. 1 but it is preferred that they completely surround the openingcircumference, and in doing so they follow the general contours of thefront face of the cuff. Flanges 20 and 21 are spaced apart slightly suchthat each flange is an integral item or unit. The flanges are spacedradially one from another around the opening such that one flangesurrounds another. The term “radially” in this context has a broadmeaning and refers to the spacing of each flange from an imaginary axisextending out of the opening in a plane substantially perpendicular tothe general plane of the cuff face.

In this embodiment two feather flanges are shown. However, there may beno flanges, one flange or two or more than two flanges. In other wordsthere may be none or a plurality of flanges, “plurality” having themeaning one or more in the context of this disclosure.

A further feature of the cuff is the epiglottic rest 30 located at theproximal end of the cuff region. This epiglottic rest is sized andshaped so as to be anatomically positioned against the epiglottis, toensure a proper seal and to hold the epiglottis back from downfoldingtowards the laryngeal inlet avoiding obstruction to airflow. Thisepiglottic rest takes the form of a leaf like structure extending out ofthe laryngeal cuff and directed back towards the proximal end of theairway tube. Its relative size and shape can be seen from 30A in FIG. 9.The optimum size and shape for this epiglottic rest will be determinedby experimentation.

Turning now to the airway tube, this is shown generally as 11 in FIG. 1.This tube, which is in the form of a hollow cylinder of substantiallyuniform cross-section open at each end, extends from the connector end12 into the body of cuff 14 to connect with cuff opening 17. The insidediameter of the airway tube will depend on the size of the device,generally larger in adult sizes versus paediatric sizes, and designed ingeneral to accommodate the appropriately sized endotracheal tube forendoscope guided intubation where necessary. The internal diameter ofthe tube may be substantially uniform along its length, although theinternal diameter may vary.

In terms of intubation the airway also has significant benefits overinflatable laryngeal cuffs during retrograde intubation procedures. Thisis because inflatable cuffs can potentially be punctured and deflated,which could result in lack of seal and problems with ventilation.

The tube is formed from a bendable plastics material that will bedescribed in more detail below. With the exception of the region at thedistal end of the tube where it starts to join the cuff, the externalprofile of the tube is substantially uniform between the distal end ofthe tube where it starts to meet the cuff and the proximal end of thetube. The term “substantially uniform” means that there is no region ofthe tube which could act as a buccal cavity stabiliser ie an expandedregion extending on either side of the airway tube. Put another way,there is no section of the tube that extends on either side of the tubeand which is generally broader in profile than the airway tube itself.The internal diameter of the airway tube will preferably besubstantially uniform and circular, whether the tube has a circular oroval exterior profile, and the distal opening of the airway tube intothe cuff is a single opening to help reduce the resistance to flowthrough the device.

The airway tube can be formed with a variety of profiles. In theembodiment illustrated in FIGS. 1 and 2 the general external profile ofthe airway tube is substantially circular. This can be seen most clearlyin FIG. 2D. In contrast, in the embodiment illustrated in FIGS. 3 and 4,the airway tube has a generally elliptical external profile, althoughthe bore passing through the airway tube is substantially circular incross-section. These are just two of many profiles that might beselected by the designer.

A connector 118 which fits into the end of the airway tube is shown inmore detail in FIG. 10. There are two important features to note fromthis embodiment. Firstly, the length of the connector is significantlygreater than a conventional connector and is such that it extends, inuse, into the patient's mouth and beyond his/her teeth. In that way itacts as a bite protector and prevents the patient from inadvertentlybiting through the relatively soft material of the airway tube. Thepatient biting down onto the airway device and particularly orcompletely occluding airflow is a problem in certain procedures and withcertain patients. Secondly, the connector fits into a recess formedwithin the airway tube by the moulding process. In this way, theinternal surface of the airway tube 109 is substantially smooth anduniform. The internal diameter of the tube from the proximal opening inthe connector to the distal end where it opens out into the cuff issubstantially uniform. There is therefore no significant step change ininternal diameter at the inner end of the connector, which leads toimproved airflow and lower resistance to flow. This arrangement is shownparticularly in FIG. 10C being a section along line E-E.

In addition to the airway tube, the embodiments shown in FIGS. 1 to 4inclusive include a second passageway 40 that extends from an opening 42in the distal end of the device to an opening 41 in the proximal end ofthe device. This second, gastric tube passageway, is designed to allowan operator to pass a gastric tube down into the stomach of a patientwithout interrupting anaesthesia, during EMS or during pre-hospitalairway management. This second passageway also allows for detection ofany gastric aspirate in the event of passive regurgitation during use.This second passageway must be large enough to allow a small boregastric tube to pass easily through the device. Typically a gastric tubepassageway would be between 6 to 14 French gauge diameter.

The gastric tube passageway 40 and 140 shown in FIGS. 1 and 3 is shownhoused substantially within the body of the airway device. However, itis also possible that this passageway could run externally of the newmain body, for example laterally or along the dorsal face of the devicebody.

Another feature of the passageways in these embodiments is that they aredisplaced to one side of the central longitudinal axis of the device, inthis case to the right-hand side of the central longitudinal axis, asviewed from the open face of the cuff. However, the passageway, which isoptional, could just as well exit along the mid-line or on the centrallongitudinal axis of the device as illustrated by 242 in FIG. 11.

A further embodiment is illustrated in FIG. 7. In this example alaryngeal cuff is formed around a pre-formed or pre-cut piece of airwaytube. This has the cost advantage that the airway tube may be formedfrom relatively inexpensive PVC tube or the like with a connector in oneend and the cuff moulded over the other end. Once again the airway tubemay be circular in profile or elliptical or any other profile asselected by the designer.

FIGS. 1B and 3B and 6B amongst others show the generally curvilinearshape of the device along its longitudinal axis. This shape is designedto correspond with the mouth/throat opening in an anaesthetised patient.Whilst the device is flexible it is resiliently deformable and tends toreturn to this concave/convex shape in its unstressed state.

In addition to passing tubes or other items through the gastric tubepassageway, it is possible to pass items such as a guide wire directlyinto the trachea through the airway tube. To facilitate this theinterior surface 150 of the cuff within the opening is ramped so as todirect a probe into the trachea (see FIG. 8C).

The device may be constructed from any suitable plastics material asselected by the materials specialist. Latex-free medical grade siliconerubber is one preferred material. The cuff should be soft in texture toavoid undue damage to the surrounding tissue. Other suitable materialsfor construction of this type of device include, but are not limited to,Poly Vinyl Chloride (PVC), Thermoplastic Elastomers such as the styrenicblock copolymers (eg Styrene Butadiene Styrene (SBS), Styrene EthyleneButylene Styrene (SEBS)), and Thermoplastic Olefin Blends (TPO),Thermoplastic PolyUrethanes (TPU), Thermoplastic Vulcanisates (TPV),Copolyester (COPE), Polyether Block Amides (PEBAX), Melt ProcessableRubbers, Flexible Co-polymers such as EVA, and foamed versions thereof,where appropriate.

A further important factor involved in the choice of a suitable materialis transparency. Ideally the material or materials of constructionshould be substantially clear or transparent. This enables theanaesthetist or operator to see the inner lumen of the airway to checkfor blockages or other problems. Such transparent materials are known tothe materials specialist.

By way of a preferred softness (hardness) range, on the Shore A scale ofHardness, a hardness of less than 30 for the face of the cuff thatcontacts the laryngeal inlet is optimum. By way of a preferred range, avalue on the same scale of between 0 to 20 is preferred, with aparticularly preferred range of 0 to 5. The apparent softness of thecuff can be further adapted by forming cavities or channels within thebody of the cuff itself.

In a further embodiment the cuff may be pre-filled with a fluid such asair, or other non-toxic gas, or a non-toxic liquid. In this context theterm fluid has a broad meaning and includes any suitable gas, liquid,vapour or mixtures or combination thereof and will be determined anddesigned by an expert in this field of anatomy/anaesthesia inconjunction with the materials specialist. The cuff will be constructedof such a material which will not allow nitrous oxide (anaesthetic gas)to diffuse through the material to any significant amount so that theextra luminal pressure is kept constant. It follows therefore that thecuff should be substantially impermeable to the fluid with which isfilled and to anaesthetic gases.

Alternatively, the cuff can be formed from a soft, foamed material orcan be foam filled. In either case this provides a soft deformable butshaped surface around the face of the cuff to engage over the anatomy ofthe laryngeal inlet region. Such a foam filled device will minimise anypotential damage to the structures in that region whilst still providinga substantially complete seal.

In the case of embodiments with a substantially circular airway tube anda gastric tube passageway which runs internally along the length of thedevice (as shown for example in FIGS. 1 and 2), the centre of the boreof the airway tube can be displaced to one side of the central ormid-line axis of the airway tube itself. This displacement providesspace for the gastric tube passageway to run alongside the bore of theairway tube. This arrangement is shown most clearly in FIG. 2D. Thegastric tube passageway is, in effect, housed within the outer body ofthe airway tube. This arrangement makes for a neat, streamlinedappearance in comparison to the arrangement in which the gastric tubepassageway is external to or mounted on the back of the device.

In terms of materials of manufacture and construction of an airwaydevice according to the present invention, it is advantageous to formthe front or open face of the cuff from a softer material than theremainder of the device. FIG. 1B shows a so-called “split line” 32between the softer plastics material on the face of the cuff andslightly firmer material on the dorsal or back part of the cuff 19. Theexact position of this split line may vary as determined by thedesigner. This line is shown in a slightly different position in FIG. 9,where it is shown as feature 132.

By moving this split line towards the dorsal face of the cuff, thisensures that the sides of the cuff 33, 34 are also made of the softermaterial. The sides are therefore more easily deformed which contributessignificantly to the ease of insertion, and removal, of the cuff duringuse. The cuff squeezes and seals into the space above the laryngealinlet, cupping the laryngeal inlet to create a good seal forventilation. As the cuff reduces in width and squeezes into position,the airway opening increases in depth. This increase in depth reducesthe likelihood of the epiglottis occluding the airway duringventilation, a problem with prior art devices.

Turning now to methods of manufacturing airway devices generally, and inparticular airway devices according to the present invention and airwaydevices as described in GB2,393,399A, several new and cost-effectivemethods have been devised. These include injection moulding the deviceas a single unit using a one-shot or a two-shot process. Such methodsalso include extruding an airway tube and injection moulding a cuffaround the tube in a one-shot or two-shot process.

It follows therefore that the airway tube may be manufactured byextrusion or injection moulding and the cuff portion may be formed byone-shot or two-shot injection moulding.

Accordingly, one method of making an airway device according to thepresent invention is to provide a mould, the mould including interiorwalls which define the shape of the airway device, and injecting intosaid mould a molten thermoplastic compound. Once cooled the item isejected from the mould. In a further embodiment a two-shot process isused in which molten thermoplastic compound of a first hardness is firstinjected into the mould, which is retained in a pre-determined positionsuch that only a pre-determined portion of the mould is filled withpolymeric material. A second molten thermoplastic compound is theninjected into the remaining space in the mould to complete the injectionmoulding process. In this manner the relatively firmer airway tube anddorsal portion of the cuff can be formed first and the relatively softerface of the cuff can be formed in the second part of the operation.Alternatively the face of the cuff can be formed first and the remainderof the device is formed in the second part of the operation.

In an alternative method an airway tube is formed in a first step,either by extrusion or cutting a pre-determined length from a longerlength of tubing. A mould defining a hollow space which will become thecuff region in the finished product is then placed around the airwaytube and thermosetting plastic is injected into the mould in a one-stepor a two-step process.

In a third manufacturing embodiment a mould defining the cuff region isused to produce a cuff by either a one-step or a two-step injectionmoulding process. The cuff produced from this mould includes a recessadapted to accept an airway tube. In a separate operation or operationsan airway tube is formed by extrusion or in some other manner. Theairway tube is then inserted into and bonded to the recess provided inthe cuff for that purpose.

According to a further method of manufacture, the moulding process maybe used to mould not only the laryngeal cuff on to the end of apre-formed airway tube, but also a soft coating over the airway tubeitself. Whilts this requires a larger mould, and more plastics material,it has the advantage that the finished device has a uniform finish oversubstantially the whole of its outer surface. It is softer for thepatient and more aesthetically appealing for the operator. Having apre-formed airway tube running most of the length of the device gives adegree of resilience and rigidity which is particularly helpful whenusing very soft plastics material.

In terms of plastics materials used in these methods of manufacture,these will be determined by the materials specialist and are generallyonly limited by the ability to bond the chosen materials together. Byway of example only, typically PVC can be used to mould the airway tube,the whole of the cuff region, the dorsal portion of the cuff region orany seals between these components. Polyolefins such as polyethylene andpolypropylene or a polyurethane can be used to form the airway tubeand/or the dorsal portion of the cuff region. A thermoplastic elastomeror a silicone rubber can be used to form the airway tube, the face ofthe cuff, the dorsal portion of the cuff, the whole of the cuff and anysecondary seals therebetween.

In this context the term “bond” has a particularly broad meaning. Itencompasses any method or process in which two or more parts arepermanently joined together. It includes, but is in no way limited to,molecular bonding, glueing using chemical adhesives, welding, includingultrasonic welding. The preferred method or methods of bonding will beselected by the materials specialist in this area.

1. An airway device for human or animal use comprising an airway tubehaving a distal end and a proximal end, the distal end of which issurrounded by a laryngeal cuff, wherein the cuff is non-inflatable andis pre-formed in a shape such that a face region of the cuff is adaptedto fit snugly over the laryngeal inlet of a patient, and wherein theexternal profile of the tube is substantially uniform between the distalend of the tube where it starts to meet the cuff and the proximal end ofthe tube, and wherein the face region of the cuff is formed from amaterial with a Shore hardness on the A scale of between 0 to
 30. 2. Anairway device as claimed in claim 1 wherein the face region of the cuffis formed from a material of Shore hardness on the A scale of between 0and
 20. 3. An airway device as claimed in claim 1 wherein the cuff isformed from a material of Shore hardness on the A scale of between 0 and5.
 4. An airway device as claimed in claim 1 wherein the profile of theairway tube is substantially circular.
 5. An airway device as claimed inclaim 1 wherein the profile of the airway tube is substantiallyelliptical.
 6. An airway device as claimed in claim 1 wherein the devicefurther comprises a gastric tube passageway extending from the distalend of the airway tube to the proximal end of the cuff.
 7. An airwaydevice as claimed in claim 6 wherein the gastric tube passageway ishoused substantially within the body of the device.
 8. An airway deviceaccording to claim 6 wherein the distal end exit of the gastric tubepassageway exits the cuff centrally, that is along the line of thecentral longitudinal axis of the device.
 9. An airway device accordingto claim 6 wherein the distal end exit of the gastric tube passageway isdisplaced to one side of the central longitudinal axis of the device.10. A device according to claim 1 wherein the device further comprisesone or more flexible flanges extending around the opening in the faceregion of the cuff.
 11. A device according to claim 10 wherein theflexible flanges extend substantially around the entire circumference ofthe opening in the cuff.
 12. A device according to claim 10 wherein aplurality of flanges are provided said flanges being space apartradially around the opening one from another such that the flanges aresubstantially concentric.
 13. A device according to claim 1 wherein saiddevice further comprises a connector adapted to connect the proximal endof the airway tube to a gas supply.
 14. A device according to claim 13wherein said connector extends into said airway tube and at least partway along the length of said airway tube to act as a bite protector toprevent a patient from constricting the airway tube by biting on it. 15.A device as claimed in claim 13 wherein said connector fits into aninternal annular recess at the proximal end of the airway tube such thatthe diameter, or internal cross-section of the airway tube where thetube is non-circular internally, remains substantially constant alongthe length of the tube when the connector is in place.
 16. An airwaydevice according to claim 15 wherein the distal end of the connectorabuts in use a shoulder in the airway tube to prevent the connector frompassing into the airway tube beyond a certain point.
 17. An airwaydevice according to claim 1 wherein the face of the laryngeal cuff isadapted to form an anatomical fit over the laryngeal inlet of a patientincorporates protuberances designed to form a good seal with thepyriform fossae and aryepiglottic folds of the laryngeal inlet of thepatient.
 18. An airway device according to claim 17 wherein the face ofthe laryngeal cuff adapted to form an anatomical fit over the laryngealinlet of a patient incorporates protuberances designed to form a goodseal with the valleculae, epiglottis, aryepiglottic folds, pyriformfossae and around the thyroid & cricoid cartilages.
 19. An airway deviceaccording to claim 1 wherein the face of the laryngeal cuff adapted tofit anatomically over the laryngeal framework of a patient incorporatesgrooves designed to allow passage of vital arteries, veins and nervessupplying the laryngeal framework.
 20. An airway device according toclaim 1 wherein the distal tip of the laryngeal cup is so sized andshaped as to remain above the upper oesophageal sphincter in use.
 21. Anairway device according to claim 20 wherein the distal tip of thelaryngeal cup is substantially concave in shape.
 22. An airway device asclaimed in claim 1 wherein the face of the laryngeal cuff and the airwaytube are formed from material of substantially the same Shore hardness.23. An airway device as claimed in claim 1 inclusive wherein the face ofthe laryngeal cuff and the airway tube are formed from materials ofdifferent Shore hardness.
 24. An airway device as claimed in claim 1inclusive wherein the airway tube together with the back or dorsal partof the cuff are made from material of one Shore hardness and the face ofthe cuff is made from a material of a different Shore hardness, suchthat the face of the cuff is made of a softer material than the airwaytube and the back or dorsal part of the cuff.
 25. (canceled)
 26. Amethod of manufacturing an airway device suitable for human or animaluse, said airway device comprising an airway tube having a distal endand a proximal end, the distal end of which is surrounded by anon-inflatable laryngeal cuff, said method comprising the steps of:— (i)providing a mould, the mould including interior walls defining aninterior volume which defines the shape of the airways device; (ii)introducing a liquid plastics material into the hollow interior volumeof the mould; (iii) optionally introducing a second liquid plasticsmaterial into said mould where it is required that the airway device ismade from materials of different Shore hardness; (iv) allowing theplastics material to solidify; (v) removing the airway device from themould.
 27. A method according to claim 26 wherein said method alsocomprises the step of inserting into said mould a connector suitable forconnecting to an anaesthetic gas supply, such that, after the mouldingprocess is complete, the connector becomes attached to the airwaydevice.
 28. A method of manufacturing an airway device suitable forhuman or animal use, said airway device comprising an airway tube havinga distal end and a proximal end, the distal end of which is surroundedby a non-inflatable laryngeal cuff, said method comprising the stepsof:— (i) providing an airway tube; (ii) providing a mould, said mouldincluding interior walls defining an interior volume which defines theshape of a laryngeal cuff; (iii) inserting said airway tube into saidmould; (iv) introducing a liquid plastics material into the hollowinterior volume of the mould; (v) optionally introducing a second liquidplastics material into said mould where it is required that the cuff ofthe airway device is made from materials of different Shore hardness;(vi) allowing the plastics material to solidify; (vii) removing theairway device from the mould.
 29. A method according to claim 28 whereinsaid airway tube is formed by an extrusion process.
 30. A method ofmanufacturing an airway device suitable for human or animal use, saidairway device comprising an airway tube having a distal end and aproximal end, the distal end of which is surrounded by a non-inflatablelaryngeal cuff, said method comprising the steps of:— (i) providing amould, the mould including interior walls defining an interior volumewhich defines the shape of a laryngeal cuff; (ii) introducing a liquidplastics material into the hollow interior volume of the mould; (iii)optionally introducing a second liquid plastics material where it isrequired that the airway device is made from materials of differentShore hardness; (iv) allowing the plastics material to solidify; (v)removing the airway device from the mould; (vi) providing an airwaytube; (vii) attaching said airway tube to said laryngeal cuff.
 31. Amethod of manufacturing an airway device suitable for human or animaluse, said airway device comprising an airway tube having a distal endand a proximal end, the distal end of which is surrounded by anon-inflatable laryngeal cuff, said method comprising the steps of:— (i)providing an airway tube; (ii) providing a mould, said mould includinginterior walls defining an interior volume which defines the shape of alaryngeal cuff and which substantially encapsulates the airway tube;(iii) inserting said airway tube into said mould; (iv) introducing aliquid plastics material into the hollow interior volume of the mould,to form the back of the cuff and substantially cover the rigid airwaytube (v) optionally introducing a second liquid plastics material intosaid mould where it is required that the cuff of the airway device ismade from materials of different Shore hardness; (vi) allowing theplastics material to solidify; (vii) removing the airway device from themould.
 32. A method according to claim 31 wherein the airway tube isformed by an extrusion process.
 33. (canceled)